Apparatus for combined cooling and aeration of biochemical-action vessels

ABSTRACT

A biochemical-action vessel accommodates a substrate in which biochemical reactions are caused by microorganisms. A heat-exchange arrangement is provided in the vessel and removes the heat generated in the substrate by such reactions. The substrate is circulated in the vessel advanced by an advancing arrangement in a closed path which passes through the heat-exchange arrangement. Aerating gaseous medium is introduced into the substrate upstream of the advancing arrangement and in the region of suction generated by the same, and entrained by the circulating substrate so as to supply the oxygen necessary for the aerobic growth of the microorganisms.

This is a continuation of application Ser. No. 966,132, filed Dec. 1,1978 now abandoned, which is a division of application Ser. No. 837,706,filed Sept. 29, 1977, now abandoned, which in turn is a division ofapplication Ser. No. 559,362, filed Mar. 17, 1975, now U.S. Pat. No.4,073,696 issued Feb. 14, 1978.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for cooling and aeratingthe contents of a vessel, and more particularly to such an apparatuswhich is used for enhancing the biochemical action of microorganisms insuch a vessel.

There are already known various arrangements for biochemically treatinga substrate, such arrangements being used either for fermentation of thesubstrate, which is usually accomplished under anaerobic conditions, orfor growing microorganisms, which is usually accomplished under aerobicconditions and where the substrate constitutes a nourishing medium. Thepresent invention is concerned with the latter type of arrangements,especially such where the substrate is a body of liquid medium.

In the arrangements of this type, which employ biochemical actionvessels in which the substrate is accommodated and acted upon by themicroorganisms, there are encountered several problems. First of all, itis necessary to introduce substantial quantities of air into thesubstrate and to thoroughly mix the air with the substrate so as toenhance the biochemical action of the microorganisms and thus theirgrowth. On the other hand, the biological action of the microorganismsresults in liberation of substantial amounts of thermal energy, thebiochemical reactions being exothermic, which thermal energy must beremoved from the substrate in order not to interfere with the furthergrowth of the microorganisms. Both of these problems must be solved inorder to present a functioning biochemical action vessel of this type,and it has been heretofore difficult to solve these problems withoutinvolving excessive expenses in terms of capital investment andoperating costs. This is due to the fact that the introduction of airinto the substrate, as well as the deprivation of the latter of heat,required substantial amounts of energy. These increased costs areespecially pronounced when the biochemical vessels are relatively large,in which case quantities in the order of several hundred cubic meters ofair must be introduced into the vessel per minute, so that the aircompressors used for delivering these substantial amounts of air musthave a power input in the order of several thousand kilowatt, whilecooling systems must be employed which have several thousand squaremeters of cooling area. All this considerably contributes to thesignificant cost of constructing and operating such an arrangement.

Various devices have already been proposed which are so constructed asto assure that the substrate will be sufficiently aerated while asufficient amount of heat will also be removed from the substrate sothat the biochemical reactions will be conducted under optimumconditions. Such devices are finding an ever-increasing application inthe field of producing nutrient and fodder proteins, that is in thefield of growing yeasts, bacteria and fungi. In the heretofore knowndevices, the problems of aerating the substrate on the one hand, and ofremoving heat from the substrate on the other hand, are for the mostpart solved independently of one another. Thus, for instance, there arealready known high-output biochemical vessels in which the heat-removalprocess is accomplished outside the vessel in that the fluid medium orsubstrate is conducted to a heat exchanger located outside the vessel,while the substrate is supplied and mixed with the air needed for thebiochemical reaction directly in the vessel. However, experience hasshown that this is disadvantageous for at least two reasons: first ofall, the microorganisms which are present in the substrate and carriedwith the same into the heat exchanger suffer in the latter an acutedeprivation of oxygen, and secondly, circulation pumps are needed whichhave a very high throughput and, consequently, a high power consumption.On the other hand, the introduction of the air into the biochemicalaction vessel proper requires a high compressor output in terms of thequantity of the air delivered and the pressure differential to beovercome and, consequently, a high power input to such a compressor.This latter is due to the fact that the compressor has to overcome arelatively high static pressure of the substrate contained in thevessel, particularly since the air is usually introduced into the vesselin the bottom region thereof in order to assure sufficient aeration ofthe entire body of the liquid in the vessel.

Another disadvantage of the conventional arrangement of this kind isthat the heat exchanger must be so constructed as to have severalthousand square meters of surface area. This results in some otherdisadvantages, in addition to the substantial cost of such a heatexchanger. Thus, for instance, in many of the arrangements of this typea plurality of pipes is employed which connect the interior of thevessel with the exterior thereof and which also serve for conducting thefluid which is to exchange heat with the environment of the heatexchanger. With such an arrangement, it is extremely difficult to locatea leak if such should occur. Also, it is very difficult to periodicallyclean the heat exchanger so as to remove deposits of the microorganismsor other substances from the same.

SUMMARY OF THE INVENTION

It is a general object of the present invention to overcome thedisadvantages of the prior art devices.

More particularly, it is an object of the present invention to providean apparatus for cooling and aerating a substrate in a biochemicalreaction vessel, which is not possessed of the drawbacks of the priorart devices of a similar kind.

It is a further object of the present invention to so construct theapparatus as to economize the operation thereof.

It is yet another object of the present invention to provide anapparatus for cooling and aerating the substrate, in which themicroorganisms are not deprived of oxygen for any substantial periods oftime.

In pursuance of these objects and others which will become apparenthereinafter, one of the features of the present invention resides, in anapparatus for cooling and aerating a substrate in a biochemical reactionvessel, In container means for receiving a fluid to be cooled andaerated, heat exchange means in the container means in contact with thefluid and operative for cooling the same, means for advancing the fluidthrough the heat-exchange means, and means for supplying aeratinggaseous medium to the advancing fluid upstream of the advancing means.More particularly, the present invention resides in an apparatus inwhich the individual elements of the heat-exchange means are associatedwith pipes for introducing air or other gaseous medium into theirvicinity, the end portions of the pipes being located in the region ofsuction generated in the fluid by the advancing means, so that the airintroduced into the above-mentioned region is entrained by thecirculating fluid.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section of a cylindrical biochemical reactionvessel according to one embodiment of the invention;

FIG. 2 is a detailed view similar to FIG. 1 showing in more detail thearrangement of the air-introducing pipes;

FIG. 3 is a top plan view of a heat exchanger of the tube-nest type tobe used in the apparatus of the present invention;

FIG. 4 is a cross-sectional view of a plate-type heat exchanger to beused in the apparatus of the present invention;

FIG. 5 is a longitudinal sectional view of a different embodiment of theapparatus of the present invention;

FIG. 6 is a longitudinal sectional view of another embodiment of theapparatus of the present invention;

FIG. 7 is a diagrammatic cross-sectional view taken on line VII--VII ofFIG. 6;

FIG. 8 is a perspective view of one section of the heat exchanger ofFIGS. 6 and 7;

FIG. 9 is a longitudinal section of a spherical apparatus of the presentinvention;

FIG. 10 is a cross-sectional view of the apparatus according to thepresent invention taken on line X-X of FIG. 9;

FIG. 11 is a longitudinal sectional view of a horizontal apparatus ofthe present invention;

FIG. 12 is a partial cross-sectional view of the apparatus taken on lineXII--XII of FIG. 11; and

FIG. 13 is a longitudinal sectional view of the apparatus taken on lineXIII--XIII of FIG. 11.

DETAILED DISCUSSION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in which the same reference numerals havebeen used for corresponding elements, and first to FIGS. 1 and 2thereof, it may be seen that the reference numeral 1 designates adiagrammatically illustrated vessel the elongation of which extends inthe upright direction. A heat exchanger 2 is accommodated in the vessel1, and it can be constituted by a nest or array of parallel tubes, ahelically coiled tube or a plurality thereof, or a plurality of tubestogether constituting a plate-shaped heat exchanger. The heat exchanger2 of this embodiment communicates with a cooling medium inlet pipe 3 anda cooling medium outlet pipe 4. A circulating or advancing arrangement5, such as a pump of conventional construction, is located underneaththe heat exchanger 2 and is driven into rotation by an electric or asimilar motor 8. The purpose of the advancing arrangement 5 is tocirculate the substrate accommodated in the vessel 1 from above to belowand through the heat exchanger 5, and simultaneously to finely dispersethe air or other gaseous medium in the substrate. The air or similargaseous medium is introduced into the vessel 1, and more particularlyinto the substrate accommodated therein, through an air inlet pipe 6,and is distributed among a plurality of air introduction pipes 9 whichare located between the various elements of the heat-exchanger 5. Amechanical froth separator 7 is provided in the upper portion of thevessel 1.

The substrate is advanced by the advancing arrangement 5 so that itflows radially outwardly of the latter and then upwardly along the wallsof the vessel 1 and outwardly along the heat exchanger 2 until itreaches the uppermost portion of the latter, whereupon the substrateenters the heat exchanger 2 through the uppermost portion thereof. Whenthe circulated substrate enters the heat exchanger 2 and flows throughthe same, drawn by the advancing arrangement 5, the air which issupplied to the air-introduction pipes 9 by the air inlet pipe 6 isentrained by the substrate and carried with the same. In one of theembodiments of the present invention, the pressure conditions in thevicinity of the outlet ends of the pipes 9 are such that subatmosphericpressure prevails in the pipes 9, so that the air is drawn into thepipes 9 and also into the pipe 6 from the exterior of the vessel withoutany need for employing a compressor or a blower at the inlet side of thepipe 6. Alternatively, the cross-section of the passages of the heatexchanger 2 in which the pipes 9 are located can be reduced in diameterso as to form a Venturi tube associated with each of the pipes 9,whereby the subatmospheric pressure prevailing in the pipes 9 and thepipe 6 is further reduced. Preferably, the advancing arrangement 5 is sodimensioned that the substrate flows through the heat exchanger 2 at aspeed of between 0.5 and 3 meters per second from above to below. Atthis velocity, the entrained air bubbles are carried by the circulatingsubstrate in the downward direction, independently of the particularheight of the heat exchanger 2. The air-introducing pipes 9 can also beequipped with small nozzles or air-distribution filters.

When it is desired that the biochemical action vessel work undersuperatmospheric pressure, it is also necessary that the introduction ofthe air into the vessel be accomplished under pressure. Within the rangeof low and moderate superatmospheric pressures, and for high volumes ofair which are required to accomplish the aeration procedure, it ispossible to utilize a conventional blower which, as well known, requiresfor its operation much lower power input than a compressor which is towork at a pressure sufficient for overcoming the static pressure of theliquid in the vessel when the air is introduced at the bottom of thevessel.

FIG. 2 illustrates the arrangement of the air introducing pipes 9 ingreater detail, as well as their location with respect to the elementsof the heat exchanger 2. The liquid mixed with the air passes through atube 11 and exits therefrom through the lower end 11a thereof. Thecooling medium is circulated in the surrounding chambers 10.

FIG. 3 illustrates a heat exchanger 2 which utilizes a nest or an arrayof parallel pipes, in cross-section, wherein the air is introduced intothe vessel 1 through the interiors of the pipes 9, while the coolingfluid circulates in the outer tube 12.

A plate heat exchanger is shown in cross-sectional view in FIG. 4. Inthis embodiment, the inlet 3 for the cooling medium is located in thelower part of the heat exchanger 2, while the outlet 4 for the coolingmedium is located in the upper part of the same. The air-introducingpipes 9 communicate with circulation chambers 13 which are surrounded bychambers 10 for the cooling medium.

FIG. 5 illustrates a modification of the vessel 1 of FIG. 1, andparticularly a modification of the air inlet system in which the air isfirst introduced into a distributor chamber 14 through two inlet pipes6, and the air is then distributed into the plurality of theair-introducing pipes 9.

A different embodiment of the biochemical action vessel 1 is showndiagrammatically in FIG. 6, wherein the vessel 1 accommodates in itsinterior segments or sections of the heat exchanger 2. The individualsections of the heat exchanger 2 are mounted on a support S which is, inturn, supported on the bottom of the vessel 1, so that the heatexchanger sections 2 are free to expand. This is particularly usefulwhen the heat exchanger 2 is subjected to radically differenttemperatures, such as the temperature during the normal use when theheat exchanger 2 cools the substrate, and the temperature to which theheat exchanger 2 and the vessel 1, respectively, are subjected as aresult of the action of hot water or steam, for instance during thesterilization thereof. The heat exchanger 2 is provided with the inletpipe 3 and the outlet pipe 4 through which the cooling medium isintroduced into and withdrawn from the heat exchanger 2 during theoperation of the vessel 1. The biochemical action vessel 1 is providedwith a lid 15 which renders possible placing, removing or replacing ofthe heat exchanger sections 2 therethrough without the need fordisassembling the vessel 1 in its entirety. The circulating arrangement5 is driven by means of an electric motor 8 of a conventionalconstruction. A guiding tube 14 is located centrally of the vessel 1,and is connected thereto in any conventional manner. The aeratinggaseous medium, such as air, is introduced into the interior of thevessel 1 through a pipe 6. The vessel 1 is constituted by an upper partand a lower part, which are connected by means of a flange 17 which canalso serve for disassembling the vessel 1 by removing the upper partthereof. A mechanical froth remover 7 is accommodated in the upper partof the vessel 1, and is energized by an electric motor 18.

During the operation of the vessel 1, the circulating arrangement 5generates a flow of the substrate through the sections of the heatexchanger 2, so that the fluid or substrate, after passing through theheat exchanger 2, enters the guiding tube 16 in the upper part thereof.The direction of flow is indicated by the arrows.

Since the vessel 1 is separated into two interconnected parts which aresealingly connected to one another by means of the flange 17, it ispossible, when necessary, to lift the upper part of the vessel 1 afterreleasing the connection between the two parts of the vessel 1. Thisaffords even better access to the various heat exchanger sections 2 thanthat afforded upon removal of the lid 15.

FIG. 7 illustrates a cross-sectional view of the vessel of FIG. 6,showing particularly clearly the sectional construction of the heatexchanger 2. The sections of the heat exchanger 2 can be provided eitherwith radially extending plates 2a, or with substantiallycircumferentially extending plates 2'.

A single section of the heat exchanger 2 is illustrated in FIG. 8,having pipes 12 and the connecting pipes 3 and 4 for circulation of thecooling medium. The section of the heat exchanger 2 is constituted by aplurality of heat-exchange plates.

A further embodiment, in many respects similar to the above-discussedembodiments, is illustrated in FIG. 9. Herein, the present invention isembodied in a spherical vessel 1. Here again, the heat exchangersections 2 are accommodated in the interior of the spherical vessel 1,and supported on the supports S. Similarly to the above embodiments, thecooling medium is supplied to the heat exchanger 2 through the inlet 3and withdrawn therefrom through the outlet 4. The substrate iscirculated in the interior of the vessel 1 by means of the advancingarrangement 5 which is driven into rotation by an electric motor, sothat the substrate passes in succession through the heat exchanger 2 andthe guiding tube 16. The aerating medium, such as air, is introducedinto the vessel 1 in the vicinity of the advancing arrangement 5 throughthe tube 6 or through a hollow shaft 5a on which the advancingarrangement 5 is mounted for shared rotation. The vessel 1 is againsubdivided into two parts which are joined by a flange 17. When theupper part of the vessel 1 is removed, the heat exchanger 2 is easilyaccessible for inspection, repair and/or replacement purposes.

FIG. 10 illustrates a cross-sectional view of the vessel 1 of FIG. 9,wherein the heat exchanger 2 is constituted by a plurality of individualsections which may again be provided with radially or circumferentiallyextending cooling elements which have been explained in connection withFIG. 7.

FIG. 11 is a longitudinal section through a further embodiment of thepresent invention, in which the vessel 1 has the shape of a cylinderwhose longitudinal axis extends substantially in the horizontaldirection. A plurality of heat exchanger sections 2 is accommodated inthe interior of the vessel 1, and these sections are again supported onsupports S. In the upper region of the vessel 1, there is provided arelatively large lid 15 which covers an opening in that region which isso dimensioned that the individual sections of the heat exchanger 2 canbe introduced into or removed from the interior of the vessel 1therethrough. The guiding tube 16, which is illustrated in the right-and left-hand regions of FIG. 11 can be dispensed with when theheat-exchanger sections 7 are so arranged as to replace the guide tube16 and to themselves serve for guiding the fluid toward the advancingarrangement 5, as illustrated in the central region of FIG. 11. Theinlet pipes 3 and the outlet pipes 4 for the cooling medium are herin soarranged as to pass through the bottom of the vessel 1. The advantage ofthis embodiment, which is in all other respects similar to theabove-discussed embodiments, is that a selected number of the advancingarrangements 5 can be accommodated in the interior of the vessel 1, themaximum number of such arrangements being determined only by practicalconsiderations, such as the maximum dimensions of the vessel 1.Similarly to the previous embodiments, one or more froth separators 7can be arranged in the upper region of the vessel 1.

FIG. 12 is a partial cross-sectional view of the biochemical actionvessel 1 described in connection with FIG. 11, showing in more detailthe arrangement of the sections of the heat exchanger 2, while FIG. 13is another longitudinal section of the same vessel 1, this time taken ina horizontal plane and showing a top plan view of the heat-exchangersections 2.

Experience with these novel biochemical action vessels as shown that itis possible to significantly simplify the construction of such vesselsand thus to reduce the capital investment connected with theconstruction of such vessels. This is advantageously achieved byconstructing the heat exchangers 2 as compact units which areaccommodated in the interior of the vessel 1. In the currently preferredembodiments of the invention, the inlet and outlet pipes for theaerating gaseous medium and for the cooling medium are so arranged thatthey can be easily connected with and disconnected from the otherelements of the assembly. Preferably, the inlet and outlet conduits passthrough the bottom wall of the vessel 1. It is further currentlypreferred that the heat-exchanger sections 2 be mounted on supports Sand connected thereto. In this manner, the various sections of the heatexchanger 2 can easily be inspected with respect to theirfluid-tightness in the vessel which has been partially opened, forinstance by removing the upper part therof, and also the sections can beeasily cleaned and, when needed, replaced.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofaerating apparatus differing from the types described above. So, forinstance, it is also possible to conduct the cooling and aeratingoperation in a container separate from the biochemical action vessel.

While the invention has been illustrated and described as embodied in anapparatus for cooling and aerating the substrate circulated in abiochemical action vessel, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can be applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as now and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:
 1. An apparatus for cooling and aerating a substrate in afermentation process, comprising a substantially cylindrical containerelongated in a substantially horizontal direction and accommodating thesubstrate to be cooled and aerated; a plurality of heat-exchangesections located in said container and each including a number ofparallel passages; means for advancing the substrate in said containerin the direction of said passages; means for supplying gaseous aeratingmedium into said passages to be entrained by the substrate advancingthrough the passages; and said heat-exchange sections encircling saidadvancing means to provide a uniform aerating and cooling of thesubstrate through said elongated container.
 2. A combination as definedin claim 1, and further comprising at least one support in saidcontainer means for supporting said heat-exchanger plates.
 3. Acombination as defined in claim 1 and further comprising a plurality ofconduits for delivering cooling medium to said heat-exchanger plates;and wherein said conduits pass through the bottom of said containermeans and are dismountably connected thereto.
 4. A combination asdefined in claim 1 wherein said container means are provided with anopening in the upper region thereof; wherein said heat-exchanger platesare introduced into said container means through said opening; andfurther comprising lid means for closing said opening.
 5. A combinationas defined in claim 1, wherein said heat-exchanger sections include aplurality of interconnected cooling pipes.